Heretofore, reactive resins such as thermosetting resins or ionizing-radiation-curing resins have been used as overcoat materials to cover the surface of paper or plastic sheet or film, or the printed surface thereof so as to protect such a material from damage by abrasion or scratch.
In order to successfully protect the above-described materials from damage by abrasion or scratch, it is necessary to make a resin to be used for coating the materials harder. In order to attain this, it has been necessary to lower the average molecular weight of crosslinked molecules of the resin. Consequently, however, the flexibility of the resin itself is lowered, so that the resin layer tends to be cracked when the substrate is bent.